Nonpolarized electromagnet system of miniature construction, especially for relays



y 24, 1966 J. FISCHER ETAL 3,

NONPOLARIZED ELECTROMAGNET SYSTEM OF MINIATURE CONSTRUCTION, ESPECIALLY FOR RELAYS Filed April 9, 1964 Claims The invention relates to a nonpolarized or neutral electromagnet system of miniature construction, especially for relays with an armature movable within a solenoid. Known electromagnet systems of this type generally have a plunger-type armature movable in an axial direction of the solenoid, which armature is operationally attracted by a soft magnetic core situated inside the solenoid, special guide means being necessarily required for the plungertype armature.

Electromagnet systems, such as are frequently required frr relays and lifting magnets, operate satisfactorily if the construction size does not fall below a certain minimum. Difiiculties, however, .arise in any attempt to appreciably reduce the size of such systems. The miniature construction utilized today in many fields of technology, however, frequently requires electromagnet systems of correspondingly small dimensions. Under the same conditions of excitation, however, there results in comparison to larger systems, lower mechanical forces at the armature. In the use of such electromagnet systems for relays, the contact forces thereby become so slight that they can no longer be regarded as suflicient for a reliable manner of operation. Lo'w contact forces, however, lead not only to high contact resistances, but there results also a considerably greater susceptibility of the contact-releasing elements to shocks.

The operational reliability of such relays in miniature construction, therefore, is considerably reduced if the usual forms constructed are employed. A reduction of the stroke traversed by the armature might compensate for the inferior efliciency caused by the size reduction of an electromagnet system of this type, but then the small contact separating distances associated therewith are frequently not permissible because the switching involves high voltages.

There exists, naturally, the possibility of raising the diminishing contact forces as the dimensions of an electromagnet system become smaller by the method of employing a correspondingly greater energizing power. Thereby, however, the self-heating of the electromagnet system is likewise raised.

It is the purpose of the invention, therefore, to create a nonpolarized electromagnet system of miniature construction with an armature movable within a solenoid, which through a favorable armature arrangement and favorable flux conduction compensates for the deterioration of the efliciency normally associated with the size reduction of such a system. An effort is made to keep the magnetic resistance of the flux circuits as low as possible and moreover to keep the mechanical friction of the armature as small as possible. The plunger core movable within a solenoid in known systems, is not free of friction because of the necessary guide means whereby the responsiveness of the system is unfavorably affected. This problem is solved according to the invention by the utilization of a soft iron armature of double-Winged form extending essentially over the whole length of the solenoid with its ends disposed opposite pole pieces supported on flux plates and extending into the iron-free core of the solenoid in diagonally offset relation. The working United States PatentO Thereby the net system extend at opposite ends of. the double-winged armature, two working air gaps being present which are .disposed in the interior of the solenoid. .The leakage flux of this electromagnet system thus is extremely low. Moreover, through the arrangement, relatively large air gap surfaces are formed in which the wedge-shaped configuration of the working air gap-s further improves the response sensitivity of the. system. In comparison with known relay systems there results thereby, despite the overall size reduction of the structure, essentially constant contact forces and equally large contact separating distances. Moreover, the response performance, as a result of the absence of'leakage flux and the favorable flux condition within the solenoid, is especially low.

In' an advantageous embodiment of the invention, the solenoid is surrounded by a soft magnetic casing having a part of the flux path which casing is magnetically connected over the flux plates with the pole pieces. Further, it is expedient that the diagonally offset pole pieces within the solenoid have the cross-sectional form of a circular segment. In order to achieve a high vibrational stability of the system, the double-winged armature will, moreover, be supported at the center of gravity.

To avoid an undesired remanence in the soft magnetic materials employed in the operation of the relay, it is advantageous to provide at one end of the double-winged armature on the side facing the adjacent pole pieces, a spacing or separating stud. At the other end of the armature there then remains for the other pole piece a smaller residual air gap. In order to be able to operate from the electromagnet system corresponding switching or control members, for example, a contact spring set, there may be provided an opening in one of the flux plates, through which opening extends an extension of the armature.

Further details of the invention will appear from the following description of an embodiment thereof illustrated in the drawing, in which:

FIGURE 1 is a longitudinal ection of the electro magnet system on a considerably enlarged scale;

FIG. 2 is a transverse sectional view taken approximately on the line IIII of FIG. 1.

The nonpolar electromagnet system of miniature construction represented in the figure comprises, a tubular nonmagnetic coil body 1 having an energizing winding 2 and a double two-Winged armature 5 swingable about the pivot point 5a, which armature is arranged approximately in axial direction inside the coil body 1. At the ends of coil body 1, two flux plates 3 and 4 'with pole pieces 3:: and 4a are disposed, in which arrangement the latter extend into the iron-free core of the coil body 1 in opposed diagonally offset relation.

These pole pieces have a cross-sectional shape in the form of a circular segment, as illustrated in FIG. 2, and are disposed opposite the somewhat offset ends of the armature 5 in such a way that in the rest position of the armature, the working air gaps have a wedge-shaped configuration. The positions of the pole surfaces of the armature 5 relative to the pole pieces 3a and 4a are such that the armature 5, when attracted on energization of the electromagnet system, is supported over a spacing stud 5b seated on one of the pole pieces while at the other pole piece there remains a small residual air gap with the armature being supported at the center of gravity.

The electromagnet system with the coil body 1 and the energizing winding 2, which is frequently designated as a solenoid, has a soft iron shell or casing 7, which is closed at its ends by respective flux plates 3 and 4. The flux plate 3 has in addition an opening 3b through which the armaguide for the excitation flux.

hire 5, by mean s of an extension member 5c, actuates the switching or control memberstnotillustrated), for example a contact spring set. Likewise, there is not illustrated in the drawing the operatively necessary return spring, which may, for example, be a torsion spring engageable at the pivot point-5a of armature 5. The possible armature stroke is designated at the extension piece 5c by the letter h.

If the energizing winding 2 is traversed by current, then there arises in the electromagnet system an excitation flux I '.whose flux paths are indicated in broken lines. From this it is apparent that the soft iron shell or casing serves not only for the mechanical protection and outer shielding of the electromagnet system, but also as a As indicated by arrows, there arises at both working air gaps 6a and 6b a torque in the same direction on the-armature 5, in which as a result of the wedge-shaped configuration of the air gaps and the relatively large oppositely situated air gap surfaces, a low magnetic resistance existsin the flux circuits. This is especially advantageous with respect to the response performance of the electromagnet system which, despite the smallness of the system, achieves a relatively high efiiciency. The construction is therefore especially suitable for miniature embodiments and in comparison to known relays of this type, for example, when fabricated with considerably smaller dimensions than prior relays, achieves equivalent contact forces and contact separation distances.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

We claim:

1. A nonpolarized electromagnet system of miniature construction, comprising a solenoid winding, a doublewinged armature disposed within said solenoid winding and extending substantially the entire length of the solenoid interior, said armature having its opposite end portions laterally offset with respect to one another and being supported at its center of gravity on an axis extending perpendicular to the solenoid axis, flux plates disposed at opposite ends of the solenoid, one of said flux plates having an opening therein through which an extension of the armature extends, for actuating members to be controlled thereby, pole pieces extending inwardly from said flux plates into the iron-free core of the solenoid in diagonally oitset relation at opposite sides of said armature, said pole pieces having a transverse cross-sectional form of a circular segment, and forming with the offset end portions of said armature respective working air gaps which, in the rest position of the armature, are of wedge-shaped configuration, and a soft magnetic shell surrounding said solenoid and connected in magnetic conduction over said flux plates with said pole pieces.

2. An electromagnet system according to claim 1, wherein there is provided at one end of the armature a spacing stud on the side facing the adjacent pole piece.

References Cited by the Examiner UNITED STATES PATENTS 2,767,357 10/1956 Naybor 317:197

2,916,584 12/1959 Molyneux. 2,951,134 8/1960 Lazich.

BERNARD A. GILHEANY, Primary Examiner.

G. HARRIS, JR., Assistant Examiner. 

1. A NONPOLARIZED ELECTROMAGNET SYSTEM OF MINIATURE CONSTRUCTION, COMPRISING A SOLENOID WINDING, A DOUBLEWINGED ARMATURE DISPOSED WITHIN SAID SOLENOID WINDING AND EXTENDING SUBSTANTIALLY THE ENTIRE LENGTH OF THE SOLENOID INTERIOR, SAID ARMATURE HAVING ITS OPPOSITE END PORTIONS LATERALLY OFFSET WITH RESPECT TO ONE ANOTHER AND BEING SUPPORTED AT ITS CENTER OF GRAVITY ON AN AXIS EXTENDING PERPENDICULAR TO THE SOLENOID AXIS, FLUX PLATES DISPOSED AT OPPOSITE ENDS OF THE SOLENOID, ONE OF SAID FLUX PLATES HAVING AN OPENING THERIN THROUGH WHICH AN EXTENSION OF THE ARMATURE EXTENDS, FOR ACTUATING MEMBERS TO BE CONTROLLED THEREBY, POLE PIECES EXTENDING INWARDLY FROM SAID FLUX PLATES INTO THE IRON-FREE CORE OF THE SOLENOID IN DIAGONALLY OFFSET RELATION AT OPPOSITE SIDES OF SAID ARMATURE, SAID POLE PIECES HAVING A TRANSVERSE CROSS-SECTIONAL FORM OF A CIRCULAR SEGMENT AND FORMING WITH THE OFFSET END PORTIONS OF SAID ARMATURE RESPECTIVE WORKING AIR GAPS WHICH, IN THE REST POSITION OF THE ARMATURE, ARE OF WEDGE-SHAPED CONFIGURATION, AND A SOFT MAGNETIC SHELL SURROUNDING SAID SOLENOID AND CONNECTED IN MAGNETIC CONDUCTION OVER SAID FLUX PLATES WITH SAID POLE PIECES. 